Self-lubricated pump with means for lubricant purification

ABSTRACT

In a centrifugal-type pump, the fluid being pressurized is extracted for use in lubricating a sleeve bearing that journals the pump rotor. The fluid is extracted through a passage exposed to the static pressure of the fluid in the pump so that contaminants are eliminated from the fluid used for lubrication.

United States Patent 1191 Partos Jan. 29, 1974 SELF-LUBRICATED PUMP WITH MEANS 3,692,426 9/1972 Ryall et a1 415/143 FOR UB N U CA 3,128,713 4/1964 Nechine 415/1 12 2,634,990 4/1953 Fink [75] Inventor: Stephen E- artos, Mamaroneck, 1,783,667 12/1930 Mueller 415/111 FOREIGN PATENTS OR APPLICATIONS Assigneel Corporation, Stratfordr Conn- 140,587 4 1951 Australia 415/112 576,267 5/1924 France 415/143 [22] 1972 153,318 11/1920 Great Britain 415 112 [21] Appl. No.: 228,162

Primary ExaminerHenry F. Raduazo [52] U S Cl us/74 415 11 (5/143 Attorney, Agent, or Firm-Charles M. Hogan. Gary 415/17OA [51] Int. Cl. F04d 17/06, F04d 29/08 [58] Field 0fSearch.. 415/170 A, 111, 143, 112, 74 [57] ABSTRACT In a centrifugal-type pump, the fluid being pressurized [56 References Cited is extracted for use in lubricating a sleeve bearing that UNITED STATES PATENTS journals the pump rotor. The fluid is extracted through a passage exposed to the static pressure of the i fluid in the pump so that contaminants are eliminated 3:l86:513 1/1965 Dunn et al. 415/112 from the fluld used for lubncamn" 3 Claims, 2 Drawing Figures 4O '46 5O 8 P 26 4 66 PAIENTEB JAN 29 L974 SELF-LUBRICATED PUMP WITI-I MEANS FOR LUBRICANT PURIFICATION The present invention relates to pumps and more particularly to a self-lubricating type of centrifugal pump.

In the pump art it has been a common practice to bleed off, whenever possible, a portion of the fluid that is being pressurized to lubricate the rotating parts of the pump. This presents a problem when the pump is pressurizing a fluid that is susceptible to contamination with abrasive particles. An example of this would be a pump used in the fuel control system of a gas turbine engine. Turbine fuel theoretically has good lubricating properties and may be used with great advantage in lubricating the rotating parts of the pump. However, in practice turbine fuel may be contaminated with a wide variety of abrasive-type particles. Normally, barriertype filters used in gas turbine fuel systems filter out the larger particulate contaminants. However, the smaller particles pass through the filters and significantly contribute to wear due to their-abrasive qualities.

When the contaminated fluid is extracted from the output of the pump to lubricate the rotating parts, it is necessary to provide an elaborate filtering device. An example of this may be found in the US. Pat. to Dunn et al, Re. 26,570. In this patent a centrifugal cyclonic separator is necessary to separate the contaminants from the fluid to be used for lubrication. A system of this type is not possible where compactness and simplicity is desired, as in the gas turbine engine.

Accordingly, it is an object 'of the present invention to provide a highly simplified effective and economical system in a centrifugal pump that supplies substantially contaminant-free fluid for lubricating the rotating parts of the pump.

These ends are achieved by a centrifugal-type pump assembly in which a bladed impeller rotates inside an annular chamber. A flow path from a point exposed to static pressure radially inward from the periphery of the chamber is provided to a means for journaling the bladed impeller so that only contaminant-free fluid passes to the journaling means.

The above and other related objects and features of the present invention will be apparent from a reading of the description of the disclosure shown in the accompanying drawing and the novelty thereof pointed out in the appended claims.

In the drawing: v

FIG. 1 is a longitudinal section view of a pump assembly embodying the present invention; and

FIG. 2 is a cross-sectional view taken on line 2-2 of FIG. 1.

Referring to FIGS. 1 and 2 there is shown a pump assembly comprising a generally cylindrical housing having a radial flange 12 to which is secured a flange 16 of an end cap 18 by screws 14. An end face 20 of the housing 10 cooperates with an interior face 22 of end cap 18 to form an annular chamber 24 generally coaxial with the end cap l8 in housing I0. An inlet passage 26 in a threaded extension 28 of end cap I8 is coappropriate outlet conduit (also not shown) carries the fluid pressurized by the pump to the desired discharge point.

A centrifugal-type impeller, generally indicated by reference character 36, is rotatable in chamber 24. lmpeller 36 comprises a support hub 38 telescopcd over a central shaft 40. A series of integral radial blades 42 extend radially from the hub 36 to a point radially inward from the periphery 25 of annular chamber 24. Webs 44 interconnect and strengthen the blades 42. A helical inducer comprising conical hub 46 and an integral helix 48 is secured to shaft and extends into inlet passage 26 for prepres'surizing fluid to be pumped by the impeller 36.

Shaft 40 isjournaled in a sleeve-type bearing 50 comprised of carbon graphite. Bearing 50 also has a face 52 which acts as a thrust bearing for the axial reaction component generated by the impeller 36. Integral flange 54 on shaft 40 abuts a seal assembly, generally indicated by reference character 56, to prevent leakage of fluid from the pump assembly. A drive shaft 58 extends from the housing 10 and is splined to receive an appropriate rotatable drive input.

In accordance with the present invention a flow path for fluid is provided from a point radially inward from the periphery 25 of chamber 24 to the sleeve bearing 50 in such a fashion that contaminant-free fluid is used for the lubrication. This is done by providing a passage 60 extending from a point radially inward from the periphery 25 of the chamber 24 (herein shown as adjacent the tips of the blades 42) extending radially inward to an annular chamber 62. Chamber 62 surrounds the longitudinal midpoint of the bearing 50. Ports 64 in bearing 50 connect chamber 62 with an annular recess 66 surrounding shaft 40. Thus, a path for pressurized fluid is provided from chamber 24 to the central portion of bearing 50. From there the fluid passes along shaft 40 to face 52 and to the region adjacent seal assembly 56. A port 68 connects to a discharge port 70 that carries away fluid from the region of the seal assembly 56 to a low pressure discharge point, such as adjacent the inlet of the pump assembly.

When the pump is in operation, fluid that may bear particulate contaminants passes through inlet 26, is pre-pressurized by the helical inducer and then is centrifuged radially outward by'the blades 42. The pressure of the fluid in chamber 24 increases in proportion Thus the inertia of the particulate contaminants carries them past passage 60 while the fluid, free from the contaminants, passes through passage 60 to the bearing where it is used to lubricate the shaft 40. The fluid leakage from the bearing assembly passes from outlet 70 to be recycled in a suitable fashion to the inlet 26.

Since the passage 60 only is exposed to static pressure, it does not extract the contaminants from themain pump flow path for lubricating purposes. The pressure in passage 60 is dependent upon the position of its inlet with respect to the central axis of the chamber. This position is preferably varied to produce the pressure which gives the precise flow of fluid necessary for lubricating purposes, thereby minimizing the amount extracted for this purpose.

While a preferred embodiment of the present invention has been illustrated, it should be apparent that the pump may be designed in different forms by those skilled in the art without departing from the spirit and scope of the present invention.

Having thus described the invention, what is claimed as novel and desired to be secured by Letters Patent of the United States is:

l. A pump assembly adapted to pump contaminated fluid, said pump assembly comprising:

a housing having a fluid inlet extending to the center of an annular chamber therein and an outlet extending from the periphery of said chamber for discharge of fluid, said chamber defined in part by a back wall opposite from said fluid inlet;

a centrifugal bladed impeller mounted on a shaft extending through said back wall and out of said housing for rotation, said impeller positioned inside said chamber and having blades with their tips spaced inward from the periphery of said annular chamber to form an annular space therebetween, said impeller receiving fluid from said inlet adjacent the axis of rotation of said impeller and centrifuging fluid for discharge-from said outlet whereby the pressure of the fluid increases proportional to its displacement from'the central axis of said chamber; a sleeve bearing positioned in said housing and surrounding the shaft of said impeller; said housing having a flow path from a radially inwardly directed inlet exposed to static pressure only radially inward and adjacent the periphery of I said chamber to said sleeve bearing, said sleeve bearing having an annular recess in the longitudinal midpoint thereof connected to said passage whereby fluid flows to both ends of said sleeve bearing from said annular recess, said inlet being positioned relative to the central axis of said chamber to be exposed to a pressure that produces the minimum flow of contaminant-free fluid necessary to lubricate said sleeve bearing;

a seal between said housing and said drive shaft for preventing the leakage'of fluid; and

a flow path extending from said housing adjacent said seal to a low pressure point.

2. A pump assembly as in claim 1 wherein said outlet extends generally tangentially from the periphery of said annular chamber.

3. A pump assembly as in claim 2 further comprising a helical inducer portion coaxial with said impeller and extending into said inlet passage for prepressurizing said fluid. 

1. A pump assembly adapted to pump contaminated fluid, said pump assembly comprising: a housing having a fluid inlet extending to the center of an annular chamber therein and an outlet extending from the periphery of said chamber for discharge of fluid, said chamber defined in part by a back wall opposite from said fluid inlet; a centrifugal bladed impeller mounted on a shaft extending through said back wall and out of said housing for rotation, said impeller positioned inside said chamber and having blades with their tips spaced inward from the periphery of said annular chamber to form an annular space therebetween, said impeller receiving fluid from said inlet adjacent the axis of rotation of said impeller and centrifuging fluid for discharge from said outlet whereby the pressure of the fluid increases proportional to its displacement from the central axis of said chamber; a sleeve bearing positioned in said housing and surrounding the shaft of said impeller; said housing having a flow path from a radially inwardly directed inlet exposed to static pressure only radially inward and adjacent the periphery of said chamber to said sleeve bearing, said sleeve bearing having an annular recess in the longitudinal midpoint thereof connected to said passage whereby fluid flows to both ends of said sleeve bearing from said annular recess, said inlet being positioned relative to the central axis of said chamber to be exposed to a pressure that produces the minimum flow of contaminant-free fluid necessary to lubricate said sleeve bearing; a seal between said housing and said drive shaft for preventing the leakage of fluid; and a flow path extending from said housing adjacent said seal to a low pressure point.
 2. A pump assembly as in claim 1 wherein said outlet extends generally tangentially from the periphery of said annular chamber.
 3. A pump assembly as in claim 2 further comprising a helical inducer portion coaxial with said impeller and extending into said inlet passage for prepressurizing said fluid. 